Re: .224 custom 100 grain ULD\'s for 1000 and 500yrd benchrest
Reed, I agree that sourcing and then getting a 100 grain ULD to work would certainly be an interesting challenge. I agree that one of the biggest problems is to co-ordinate the barrel twist with the rpm's the bullet jacket can withstand.
I believe that a 1 in 6.5 twist would stabilise the 100 grain Wildcat RBULD at 3100 - 3200 fps but that a 1 in 7 twist may be marginal at that velocity.
I am not familiar with the number of shots fired in a given time in 500 an 1000 yard benchrest match. However, my biggest concern would be the rate of fire, and as you would have already discovered with you 22/243 AI, 3 shots in 3 minutes and your barrel is hot. So if you have to fire at that pace, then I suggest that you use a much smaller case.
I am also a devotee of the "big 22's", and since 1972 have owned a 22/250, 22/250AI, 220 Swift, 220 Swift AI, 22/284, and about to build up another .224 Clark.
Richard Graves forwarded to me by surface mail his 80 and 85 grain RBULD's about 10 days ago, but it will be another 4 weeks or thereabouts before I get them here in "Oz". I originally ordered some ULD's of 85 grains and whatever was the heaviest his dies and jackets could produce, but after some experimenting he found that 85 grains was the limit.
Richard also mentioned that he could make some 90 and 100 grain 10 ogive flat base HP's, and I asked him to send me some in the next shipment with the 125 grain 257 ULD's, and I would try them. He thought that the Krieger 26 inch 1 in 7 twist barrel which I will be ordering this week should stabilise both his 85 grain ULD and the 90 and 100 grain flat base 10 ogive HP.
I will base the rifle around the 80 grain Sierra HPBT as I still have 450 left, and several others have reported that they shoot accurately and hold together well in a 1 in 7 twist barrel at 3600+ fps. I will experiment with the bullet weights of 85+ grains and see what happens.
I discovered in my first .224 Clark, that the Rem 700 short action magazine box length of 2.800 is too short, so I now have to find a second hand Rem 700 BDL rifle in 270, 280, etc to source the action for .224 Clark (number 2).
My first 224 Clark achieved 3730 fps with the 80 grain Sierra in a 25.25 inch barrel, so this time around, I estimate that the 85 grain ULD should get around 3650 fps, and with the 90 grain JLK or Wildcat FBHP around 3550 fps, and 100 grain FBHP about 3,350fps.
Several years ago, I emailed Corbins regarding making 80 - 90 grain ULD's, and Dave Corbin when replying said " You would need to draw down a .257 jacket to .224 for a 90 grain weight. It works rather well. We have made many sets of these recently, as the current trend leans toward exactly what you ask about."
I would be interested to hear how your project progresses. Regards, Brian.